Fix 1992/albert README
The README.md had an email to the judges from Leo (prior to being a judge, presumably) which means that the index file would not end up with information about the entry. The old contents of the README.md were copied to albert.bug.md though perhaps it should not be a markdown file. The name was arbitrarily selected and a better name could certainly be contrived.
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@@ -1,22 +1,85 @@
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From: leo _at_ zycad -dot- com (Leo Broukhis)
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Date: Tue, 30 Jan 96 17:37:51 PST
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To: judges _at_ toad -dot- com
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Subject: IOCCC 1992 - a bug
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Most Useful Program:
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Dear Judges,
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Albert van der Horst
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S P&A R&C
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Oranjestraat 8
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3511 RA UTRECHT
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The Netherlands
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albert.c (even in its fixed form) still has a bug. Although I don't
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remember the number that exposed the bug (afair, resulting in coredump)
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in albert.orig.c that has been fixed in albert.c,
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I've found a number exposing another bug: 10000000001 (that's 9 0's).
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Both albert and albert.orig loop without printing anything, although
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the first factor is 101 and is usually found in an instant.
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Unfortunately, the e-mail address in albert.hint is no longer valid,
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and neither whois, nor replacing old domain name with a new one according
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to the MX records, nor Altavista Web search were successful.
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Judges' comments:
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...Fortunately, Albert van der Horst did send me an unobfuscated
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(but somewhat limited - it doesn't check the number for factors 2, 3, 5, 7)
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version of his program. I didn't have a chance to augment its functionality
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to the one of the contest entry.
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For a canned example:
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make albert
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albert 1234567890123456789
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We were impressed with the speed at which it was able to factor
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arbitrarily large numbers consisting of factors that fit into
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a long.
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Selected notes from the author:
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The Obfuscated version of the Horst algorithm.
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This program will factor unlimited length numbers and print the
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factors in ascending order. Numbers of one digit (e.g. 8)
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are rejected without notice.
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It quits as soon as there is at most one
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factor left, but that factor will not be shown.
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It accomplishes this efficiently, without resorting to division
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or multiplication, until the candidate factor no longer fits in
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a signed long.
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The nicest way is to rename the program into e.g. 4294967297
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if you want to factor Fermat's 4th number. Then just run it.
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Or you may type "prog <some-number>"
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A nice one is also (30 ones)
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albert 111111111111111111111111111111
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Apart from the foregoing there are no special execution instructions.
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To customize the program into a factorizer of a fixed number, use
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cc albert.c -o 4294967297
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or some such.
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There are no data files used, and it is not possible to feed input
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via stdin.
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I think this program is a nice example of algorithmic obfuscation.
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Several times two similar algorithms are merged into one. Then you
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need quite some tricks to get it running, such as long jumps
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through recursive subroutines. I felt like a sword smith,
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welding the sword very long, folding it again to the proper
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length, keep on hammering till it is tight, then fold again.
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Always keeping it at the proper red hot temperature, but not too
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hot lest the hardness fades.
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The strict naming conventions for subroutines did not make things
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much clearer after all, but it was not supposed to.
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I would like to draw attention to the robustness of the program
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with respect to error handling and the nice stopping criterion.
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The esthetic appeal of some lines is at the expense of clearness,
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I apologize.
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Running the program through the c-beautifier reveals nothing,
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it will only destroy some of the lay out.
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Running the program through lint shows the usual remarks for a
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K&R program. Defeating this through casts does not make a program
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cleaner in my opinion.
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Here are some hints, but they may not be too helpful.
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1. The Horst algorithm is described in the Hobby Computer Club
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Newsletter, year 82, part 4, a real Dutch treat.
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Assembler, c and Forth version have been around for some years.
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2. Does fractal programming exist after all?
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3. You remember the ToomCook algorithm in Knuth?
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It uses iteration instead of recursion and is quite jumpy.
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This program shares these disadvantages in a modified form.
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4. The Conversion is to be found in Knuth, not so the Observation.
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The Observation: "if it ends in a zero, it is divisible by ten"
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Copyright (c) 1992, Landon Curt Noll & Larry Bassel.
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All Rights Reserved. Permission for personal, educational or non-profit use is
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granted provided this this copyright and notice are included in its entirety
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and remains unaltered. All other uses must receive prior permission in writing
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from both Landon Curt Noll and Larry Bassel.
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@@ -0,0 +1,22 @@
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From: leo _at_ zycad -dot- com (Leo Broukhis)
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Date: Tue, 30 Jan 96 17:37:51 PST
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To: judges _at_ toad -dot- com
|
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Subject: IOCCC 1992 - a bug
|
||||
|
||||
Dear Judges,
|
||||
|
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albert.c (even in its fixed form) still has a bug. Although I don't
|
||||
remember the number that exposed the bug (afair, resulting in coredump)
|
||||
in albert.orig.c that has been fixed in albert.c,
|
||||
I've found a number exposing another bug: 10000000001 (that's 9 0's).
|
||||
Both albert and albert.orig loop without printing anything, although
|
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the first factor is 101 and is usually found in an instant.
|
||||
|
||||
Unfortunately, the e-mail address in albert.hint is no longer valid,
|
||||
and neither whois, nor replacing old domain name with a new one according
|
||||
to the MX records, nor Altavista Web search were successful.
|
||||
|
||||
...Fortunately, Albert van der Horst did send me an unobfuscated
|
||||
(but somewhat limited - it doesn't check the number for factors 2, 3, 5, 7)
|
||||
version of his program. I didn't have a chance to augment its functionality
|
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to the one of the contest entry.
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@@ -1,85 +0,0 @@
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Most Useful Program:
|
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|
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Albert van der Horst
|
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S P&A R&C
|
||||
Oranjestraat 8
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3511 RA UTRECHT
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The Netherlands
|
||||
|
||||
|
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Judges' comments:
|
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|
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For a canned example:
|
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make albert
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albert 1234567890123456789
|
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|
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We were impressed with the speed at which it was able to factor
|
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arbitrarily large numbers consisting of factors that fit into
|
||||
a long.
|
||||
|
||||
|
||||
Selected notes from the author:
|
||||
|
||||
The Obfuscated version of the Horst algorithm.
|
||||
|
||||
This program will factor unlimited length numbers and print the
|
||||
factors in ascending order. Numbers of one digit (e.g. 8)
|
||||
are rejected without notice.
|
||||
It quits as soon as there is at most one
|
||||
factor left, but that factor will not be shown.
|
||||
It accomplishes this efficiently, without resorting to division
|
||||
or multiplication, until the candidate factor no longer fits in
|
||||
a signed long.
|
||||
|
||||
The nicest way is to rename the program into e.g. 4294967297
|
||||
if you want to factor Fermat's 4th number. Then just run it.
|
||||
Or you may type "prog <some-number>"
|
||||
A nice one is also (30 ones)
|
||||
albert 111111111111111111111111111111
|
||||
|
||||
Apart from the foregoing there are no special execution instructions.
|
||||
|
||||
To customize the program into a factorizer of a fixed number, use
|
||||
cc albert.c -o 4294967297
|
||||
or some such.
|
||||
|
||||
There are no data files used, and it is not possible to feed input
|
||||
via stdin.
|
||||
|
||||
I think this program is a nice example of algorithmic obfuscation.
|
||||
Several times two similar algorithms are merged into one. Then you
|
||||
need quite some tricks to get it running, such as long jumps
|
||||
through recursive subroutines. I felt like a sword smith,
|
||||
welding the sword very long, folding it again to the proper
|
||||
length, keep on hammering till it is tight, then fold again.
|
||||
Always keeping it at the proper red hot temperature, but not too
|
||||
hot lest the hardness fades.
|
||||
The strict naming conventions for subroutines did not make things
|
||||
much clearer after all, but it was not supposed to.
|
||||
|
||||
I would like to draw attention to the robustness of the program
|
||||
with respect to error handling and the nice stopping criterion.
|
||||
The esthetic appeal of some lines is at the expense of clearness,
|
||||
I apologize.
|
||||
Running the program through the c-beautifier reveals nothing,
|
||||
it will only destroy some of the lay out.
|
||||
Running the program through lint shows the usual remarks for a
|
||||
K&R program. Defeating this through casts does not make a program
|
||||
cleaner in my opinion.
|
||||
|
||||
Here are some hints, but they may not be too helpful.
|
||||
1. The Horst algorithm is described in the Hobby Computer Club
|
||||
Newsletter, year 82, part 4, a real Dutch treat.
|
||||
Assembler, c and Forth version have been around for some years.
|
||||
2. Does fractal programming exist after all?
|
||||
3. You remember the ToomCook algorithm in Knuth?
|
||||
It uses iteration instead of recursion and is quite jumpy.
|
||||
This program shares these disadvantages in a modified form.
|
||||
4. The Conversion is to be found in Knuth, not so the Observation.
|
||||
The Observation: "if it ends in a zero, it is divisible by ten"
|
||||
|
||||
Copyright (c) 1992, Landon Curt Noll & Larry Bassel.
|
||||
All Rights Reserved. Permission for personal, educational or non-profit use is
|
||||
granted provided this this copyright and notice are included in its entirety
|
||||
and remains unaltered. All other uses must receive prior permission in writing
|
||||
from both Landon Curt Noll and Larry Bassel.
|
||||
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